FIB-SEM imaging of carbon nanotubes in mouse lung tissue

Ultrastructural characterisation is important for understanding carbon nanotube (CNT) toxicity and how the CNTs interact with cells and tissues. The standard method for this involves using transmission electron microscopy (TEM). However, in particular, the sample preparation, using a microtome to cut thin sample sections for TEM, can be challenging for investigation of regions with agglomerations of large and stiff CNTs because the CNTs cut with difficulty. As a consequence, the sectioning diamond knife may be damaged and the uncut CNTs are left protruding from the embedded block surface excluding them from TEM analysis. To provide an alternative to ultramicrotomy and subsequent TEM imaging, we studied focused ion beam scanning electron microscopy (FIB-SEM) of CNTs in the lungs of mice, and we evaluated the applicability of the method compared to TEM. FIB-SEM can provide serial section volume imaging not easily obtained with TEM, but it is time-consuming to locate CNTs in the tissue. We demonstrate that protruding CNTs after ultramicrotomy can be used to locate the region of interest, and we present FIB-SEM images of CNTs in lung tissue. FIB-SEM imaging was applied to lung tissue from mice which had been intratracheally instilled with two different multiwalled CNTs; one being short and thin, and the other longer and thicker. FIB-SEM was found to be most suitable for detection of the large CNTs (Ø ca. 70 nm), and to be well suited for studying CNT agglomerates in biological samples which is challenging using standard TEM techniques. [Figure: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00216-013-7566-x) contains supplementary material, which is available to authorized users

No association of alcohol use and the risk of ulcerative colitis or Crohn’s disease: data from a European Prospective cohort study (EPIC)

Background The role of long -term alcohol consumption for the risk of developing ulcerative colitis (UC) and Crohn’s disease (CD) is unclear. Aim s For the first time, t o prospectively assess the role of pre -disease alcohol consumption o n the risk of developing UC or CD. Methods Nested within the European Prospective Investigation into Cancer and Nutrition (EPIC - IBD ), incident UC and CD cases and ma tched controls where included. At recruitment, participants completed validated food frequency and lifestyle questionnaires. Alcohol consumption was classified as either: non -use, former, light ( ≤ 0.5 and 1 drink/week), below the recommended limits (BRL) ( ≤ 1 and 2 drinks/day), moderate ( ≤ 2.5 and 5 drinks/day) , or heavy use (>2.5 and >5 drinks/ day) for women and men, respectively ; and was expressed as consumption at enrolment and during lifetime. Conditional logistic regression was applied adjusting for smoking and education , taking light users as the 3 Abstract Background The role of long -term alcohol consumption for the risk of developing ulcerative colitis (UC) and Crohn’s disease (CD) is unclear. Aim s For the first time, t o prospectively assess the role of pre -disease alcohol consumption o n the risk of developing UC or CD. Methods Nested within the European Prospective Investigation into Cancer and Nutrition (EPIC - IBD ), incident UC and CD cases and ma tched controls where included. At recruitment, participants completed validated food frequency and lifestyle questionnaires. Alcohol consumption was classified as either: non -use, former, light ( ≤ 0.5 and 1 drink/week), below the recommended limits (BRL) ( ≤ 1 and 2 drinks/day), moderate ( ≤ 2.5 and 5 drinks/day) , or heavy use (>2.5 and >5 drinks/ day) for women and men, respectively ; and was expressed as consumption at enrolment and during lifetime. Conditional logistic regression was applied adjusting for smoking and education , taking light users as the reference. Results Out of 262,451 participants in 6 countries, 198 UC incident cases/792 controls and 84 CD cases/336 controls were included. At enrolment, 8%/27%/3 2%/2 3%/1 1% UC cases and 7%/2 9%/4 0%/19%/ 5% C D cases were: non -users, light, BRL, moderate and heavy users, respectively. The corresponding figures for lifetime non -use, former, light, BRL, moderate and heavy use were : 3%/5%/2 3%/44%/19%/6% and 5%/2%/25%/44%/23 %/1% for UC and CD cases , respectively. There were no associations between any categories of alcohol consumption and risk of UC or CD in the una djusted and adjusted odds ratios . Conclusion There was no evidence of association s between alcohol use and the odds of developing either UC or CD

A membrane-inserted structural model of the yeast mitofusin Fzo1

Mitofusins are large transmembrane GTPases of the dynamin-related protein family, and are required for the tethering and fusion of mitochondrial outer membranes. Their full-length structures remain unknown, which is a limiting factor in the study of outer membrane fusion. We investigated the structure and dynamics of the yeast mitofusin Fzo1 through a hybrid computational and experimental approach, combining molecular modelling and all-atom molecular dynamics simulations in a lipid bilayer with site-directed mutagenesis and in vivo functional assays. The predicted architecture of Fzo1 improves upon the current domain annotation, with a precise description of the helical spans linked by flexible hinges, which are likely of functional significance. In vivo site-directed mutagenesis validates salient aspects of this model, notably, the long-distance contacts and residues participating in hinges. GDP is predicted to interact with Fzo1 through the G1 and G4 motifs of the GTPase domain. The model reveals structural determinants critical for protein function, including regions that may be involved in GTPase domain-dependent rearrangements

The restorative role of annexin A1 at the blood–brain barrier

Annexin A1 is a potent anti-inflammatory molecule that has been extensively studied in the peripheral immune system, but has not as yet been exploited as a therapeutic target/agent. In the last decade, we have undertaken the study of this molecule in the central nervous system (CNS), focusing particularly on the primary interface between the peripheral body and CNS: the blood–brain barrier. In this review, we provide an overview of the role of this molecule in the brain, with a particular emphasis on its functions in the endothelium of the blood–brain barrier, and the protective actions the molecule may exert in neuroinflammatory, neurovascular and metabolic disease. We focus on the possible new therapeutic avenues opened up by an increased understanding of the role of annexin A1 in the CNS vasculature, and its potential for repairing blood–brain barrier damage in disease and aging

MFN1 structures reveal nucleotide-triggered dimerization critical for mitochondrial fusion

Mitochondria are double-membraned organelles with variable shapes influenced by metabolic conditions, developmental stage, and environmental stimuli. Their dynamic morphology is a result of regulated and balanced fusion and fission processes. Fusion is crucial for the health and physiological functions of mitochondria, including complementation of damaged mitochondrial DNAs and the maintenance of membrane potential. Mitofusins are dynamin-related GTPases that are essential for mitochondrial fusion. They are embedded in the mitochondrial outer membrane and thought to fuse adjacent mitochondria via combined oligomerization and GTP hydrolysis. However, the molecular mechanisms of this process remain unknown. Here we present crystal structures of engineered human MFN1 containing the GTPase domain and a helical domain during different stages of GTP hydrolysis. The helical domain is composed of elements from widely dispersed sequence regions of MFN1 and resembles the ‘neck’ of the bacterial dynamin-like protein. The structures reveal unique features of its catalytic machinery and explain how GTP binding induces conformational changes to promote GTPase domain dimerization in the transition state. Disruption of GTPase domain dimerization abolishes the fusogenic activity of MFN1. Moreover, a conserved aspartate residue trigger was found to affect mitochondrial elongation in MFN1, probably through a GTP-loading-dependent domain rearrangement. Thus, we propose a mechanistic model for MFN1-mediated mitochondrial tethering, and our results shed light on the molecular basis of mitochondrial fusion and mitofusin-related human neuromuscular disorders

Multitrait analysis of quantitative trait loci using Bayesian composite space approach

<p>Abstract</p> <p>Background</p> <p>Multitrait analysis of quantitative trait loci can capture the maximum information of experiment. The maximum-likelihood approach and the least-square approach have been developed to jointly analyze multiple traits, but it is difficult for them to include multiple QTL simultaneously into one model.</p> <p>Results</p> <p>In this article, we have successfully extended Bayesian composite space approach, which is an efficient model selection method that can easily handle multiple QTL, to multitrait mapping of QTL. There are many statistical innovations of the proposed method compared with Bayesian single trait analysis. The first is that the parameters for all traits are updated jointly by vector or matrix; secondly, for QTL in the same interval that control different traits, the correlation between QTL genotypes is taken into account; thirdly, the information about the relationship of residual error between the traits is also made good use of. The superiority of the new method over separate analysis was demonstrated by both simulated and real data. The computing program was written in FORTRAN and it can be available for request.</p> <p>Conclusion</p> <p>The results suggest that the developed new method is more powerful than separate analysis.</p

Risk factors associated with fatal pulmonary hemorrhage in locally advanced non-small cell lung cancer treated with chemoradiotherapy

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to identify the risk factors associated with fatal pulmonary hemorrhage (PH) in patients with locally advanced non-small cell lung cancer (NSCLC), treated with chemoradiotherapy.</p> <p>Methods</p> <p>The medical records of 583 patients with locally advanced NSCLC, who were treated with chemoradiotherapy between July 1992 and December 2009 were reviewed. Fatal PH was defined as PH leading to death within 24 h of its onset. Tumor cavitation size was defined by the cavitation diameter/tumor diameter ratio and was classified as minimum (< 0.25), minor (≥ 0.25, but < 0.5), and major (≥ 0.5).</p> <p>Results</p> <p>Of the 583 patients, 2.1% suffered a fatal PH. The numbers of patients with minimum, minor, and major cavitations were 13, 11, and 14, respectively. Among the 38 patients with tumor cavitation, all 3 patients who developed fatal PH had major cavitations. On multivariate analysis, the presence of baseline major cavitation (odds ratio, 17.878), and a squamous cell histology (odds ratio, 5.491) proved to be independent significant risk factors for fatal PH. Interestingly, all patients with fatal PH and baseline major cavitation were found to have tumors with squamous cell histology, and the occurrence of fatal PH in patients having both risk factors was 33.3%.</p> <p>Conclusions</p> <p>Patients at high risk of fatal PH could be identified using a combination of independent risk factors.</p

Autophagy and Exosomes in the Aged Retinal Pigment Epithelium: Possible Relevance to Drusen Formation and Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a major cause of loss of central vision in the elderly. The formation of drusen, an extracellular, amorphous deposit of material on Bruch's membrane in the macula of the retina, occurs early in the course of the disease. Although some of the molecular components of drusen are known, there is no understanding of the cell biology that leads to the formation of drusen. We have previously demonstrated increased mitochondrial DNA (mtDNA) damage and decreased DNA repair enzyme capabilities in the rodent RPE/choroid with age. In this study, we found that drusen in AMD donor eyes contain markers for autophagy and exosomes. Furthermore, these markers are also found in the region of Bruch's membrane in old mice. By in vitro modeling increased mtDNA damage induced by rotenone, an inhibitor of mitochondrial complex I, in the RPE, we found that the phagocytic activity was not altered but that there were: 1) increased autophagic markers, 2) decreased lysosomal activity, 3) increased exocytotic activity and 4) release of chemoattractants. Exosomes released by the stressed RPE are coated with complement and can bind complement factor H, mutations of which are associated with AMD. We speculate that increased autophagy and the release of intracellular proteins via exosomes by the aged RPE may contribute to the formation of drusen. Molecular and cellular changes in the old RPE may underlie susceptibility to genetic mutations that are found in AMD patients and may be associated with the pathogenesis of AMD in the elderly

Mitochondrial fragmentation and superoxide anion production in coronary endothelial cells from a mouse model of type 1 diabetes

Mitochondria frequently change their shapes by fusion and fission and these morphological dynamics play important roles in mitochondrial function and development as well as programmed cell death. The goal of this study is to investigate whether: (1) mitochondria in mouse coronary endothelial cells (MCECs) isolated from diabetic mice exhibit increased fragmentation; and (2) chronic treatment with a superoxide anion (O2 −) scavenger has a beneficial effect on mitochondrial fragmentation in MCECs. MCECs were freshly isolated and lysed for protein measurement, or cultured to determine mitochondrial morphology and O2 − production. For the ex vivo hyperglycaemia experiments, human coronary endothelial cells were used. Elongated mitochondrial tubules were observed in MCECs isolated from control mice, whereas mitochondria in MCECs from diabetic mice exhibited augmented fragmentation. The level of optic atrophy 1 (OPA1) protein, which leads to mitochondrial fusion, was significantly decreased, while dynamin-related protein 1 (DRP1), which leads to mitochondrial fission, was significantly increased in MCECs from diabetic mice. Diabetic MCECs exhibited significantly higher O2 − concentrations in cytosol and mitochondria than control MCECs. Administration of the O2 − scavenger TEMPOL to diabetic mice for 4 weeks led to a significant decrease in mitochondrial fragmentation without altering the levels of OPA1 and DRP1 proteins in MCECs. High-glucose treatment for 24 h significantly induced mitochondrial fragmentation, which was restored by TEMPOL treatment. In addition, excess O2 − production, either in cytosol or in mitochondria, significantly increased mitochondrial fragmentation. These data suggest that lowering the O2 − concentration can restore the morphological change in mitochondria and may help improve mitochondrial function in diabetic MCECs